Debugging with GDB Manual (5900-1473; WDB 6.2; January 2011)

(page 118), for a discussion of how GDB reads
symbols (in the description of symbol-file).
set symbol-reloading on Tell GDB to replace symbol definitions for the
corresponding source file when an object file with
a particular name is seen again.
set symbol-reloading off Tell GDB not to replace the symbol definitions
when encountering object files of the same name
more than once. This is the default state; if you
are not running on a system that permits automatic
re-linking of modules, you must leave
symbol-reloading off. Otherwise, GDB may
discard symbols when linking large programs,
that may contain several modules (from different
directories or libraries) with the same name.
show symbol-reloading Display the current status of
symbol-reloading.
112 Examining the Symbol Table